1. Field of invention
This invention relates to an ink-jet recording apparatus and more particularly to a carriage locking mechanism for locking a recording-head carrying carriage.
2. Related art
An ink-jet recording apparatus is used for printing on a recording medium by sending a jet of ink drops out of ink nozzles of a recording head while reciprocating a recording-head carrying carriage within a predetermined range. When no printing is occurring, the carriage is kept on stand-by in the home position outside the printing range. In the stand-by condition, the nozzle-forming surface of the recording head is covered with a cap to prevent increasing ink viscosity as the ink dries, or to prevent entrance of air from the outside. While the recording head is covered with the cap, an ink suction pump is driven periodically to discharge thickened ink and air outside by sucking the ink from the ink nozzles of the recording head. In addition, an elastic blade is used to wipe off foreign materials such as paper dust and ink sticking to the nozzle-forming surface of the recording head.
When ink is sucked from the recording head by driving the ink suction pump, the recording head must be set at the predetermined position so that the cap will not slip off the recording head. It is then necessary to lock the carriage containing the recording head in the home position and prevent the cap from undesirably slipping off the recording head. In the home position, the carriage can often be released from this position due to vibration, shock, a power cut or the like.
Mounting the ink suction pump, the carriage locking mechanism, and the head wiping member tends to increase not only the dimensions of the apparatus but also its production cost to the extent that they are mounted. It is therefore desirable to make such mechanisms as an ink suction pump, a carriage locking mechanism and a mechanism for driving a head wiping member small-sized and compact.
Various implementations of the invention may include one or more of the following features.
In general, in one aspect, the invention features an ink-jet recording apparatus that performs printing of images or characters on a recording medium by moving a carriage having a recording head for ejecting ink drops, which includes a locking mechanism capable of locking the carriage in a predetermined position, an ink suction pump for sucking ink from ink nozzles of the recording head while the carriage is set at the predetermined position, a head wiping member for wiping off foreign materials from the nozzle-forming surface of the recording head which moved by the carriage, and a driving mechanism for common use in driving the locking mechanism, the ink suction pump and the head wiping member.
In an implementation, the head wiping member may include an elastic blade capable of moving between a forward position where the head wiping member is in contact with the nozzle-forming surface and a backward position where the head wiping member is away from the nozzle-forming surface, and the locking mechanism may also include a locking lever having an engaging portion is capable of moving between a locked position where the engaging portion is engaged with the carriage and an unlocked position where engaging portion is release therefrom.
In another implementation, the driving mechanism may include a motor and a power transmission mechanism for transmitting the driving force of the motor to the ink suction pump, the locking lever and the elastic blade, and the power transmission mechanism may also include a rotary-motion transmission mechanism for transmitting the rotary motion of the motor to the ink suction pump, a first conversion mechanism for converting the rotary motion into the reciprocating movement of the elastic blade, and a second conversion mechanism for converting the reciprocating movement of the elastic blade into the locking motion of the locking arm.
In another implementation, the rotary motion of the rotary-motion transmission mechanism is transmitted to the first conversion mechanism by the frictional force obtained from a spring member. With this arrangement, there occurs a slide between the rotary-motion transmission mechanism and the first conversion mechanism when the movement of the elastic blade or the locking arm as a driven member is blocked, and the rotary motion is not transmitted. Therefore, the driving control of each portion can be accomplished by a simple mechanism because the elastic blade or the locking arm as a driven member can be stopped at any desired position, irrespective of the driving condition of the motor or the ink suction pump.
In order to drive the ink suction pump, on the other hand, the carriage needs locking by means of the locking arm prior to driving the ink suction pump. When the elastic blade is used to wipe the recording head, however, the carriage will have to be moved by releasing the locked condition of the carriage while the elastic blade is held in the forward position.
In another implementation, a mechanism is provided for converting the reciprocating movement of the reciprocating member on the elastic blade side by means of the second conversion mechanism into the locking motion of the locking arm, the locking motion of the locking arm is regulated so that when the elastic blade advances up to the mid position between the backward and forward positions, the locking arm will rock from the unlocked position up to the locked position and that when the elastic blade advances further up to the forward position, the locking arm will rock up to the unlocked position.
In another implementation, the rotary-motion transmission mechanism may include a gear train for coupling the motor and the ink suction pump, the first conversion mechanism may include a rotary cam plate which is press-fixed coaxially by spring force to a driving gear included in the gear train, an arcuate cam groove formed on the side of the rotary cam plate, a cam follower which is slidable in the arcuate cam groove, a reciprocating member with the cam follower fitted to the rear end of the reciprocating member, and a guide portion for supporting the reciprocating member between the forward and backward positions so that the reciprocating member may reciprocate linearly, and the second conversion mechanism may also include a locking-arm engaging portion fitted to the reciprocating member, a locking shaft for supporting the locking arm so as to make the locking arm capable of locking within a predetermined angle range, and an engaging portion engaging with the locking-arm engaging portion.
In another implementation, the ink suction pump may include a circular inner circumferential face, a flexible ink tube which is placed along the circular inner circumferential face, a roller, and a cam roller which is rolled along the circular inner circumferential face while the roller is held against the ink tube. In this case, the driving gear is coupled to the cam rotor of the ink suction pump so that the driving gear may be rotated in a way integral therewith when the locking arm reaches the locking position after the rotary cam plate of the first conversion mechanism together with the driving gear of the rotary-motion transmission mechanism is rotated by a predetermined angle.
The invention may provide one or more of the following advantages.
As set forth above, the driving mechanism for common use is employed for driving the ink suction pump, the carriage locking mechanism and the head wiping member, so that the ink-jet recording apparatus can be made small-sized and less costly by utilizing a common power transmission path for driving each portion, in comparison with the provision of individual driving mechanisms. Moreover, control of driving each portion becomes simplified because any operation to time the driving of the individual driving mechanisms can be dispensed with.
Further details of an ink jet recording apparatus suitable for use in further embodiments are disclosed in US application entitled, xe2x80x9cInk Jet Recording Apparatus and Methodxe2x80x9d, assigned to the same assignee, Seiko-Epson Corporation, filed on the same date, and with priority based on Japanese Patent Application Hei. 10-201010, filed Jul. 15, 1998.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and the drawings, and from the claims.